1. Field of the Invention
This invention relates generally to novel fuel additives and fuel compositions containing these additives. More specifically, the invention relates to a storage stable fuel composition comprising a major amount of a fuel and a minor amount of a metal compound and an oxime.
2. State of the Art
The use of various metal compounds, particularly transition metal compounds such as compounds of manganese, lead, copper, zinc, cobalt and nickel, to name a few, in fuels to reduce soot formation and improve combustion properties of the fuel has been well documented. For example, in U.S. Pat. No. 2,338,578, the use of chromium soaps over other transition metal compounds in heating fuel oil is disclosed for the purpose of improving the combustion characteristics of the fuel oil. In U.S. Pat. No. 2,560,542, the use of combinations of two separate transition elements in a dispersible form in fuels to improve the combustion characteristics of the fuel is disclosed. U.S. Pat. No. 3,348,932 discloses a very specific combination of metal compounds to improve the combustion characteristics of fuels and reduce soot formation.
The problem associated with adding such metal compounds to fuels, as disclosed in the foregoing patents, is that the fuel is not stable upon storage. Fuels containing such metal compounds will form gummy or sludge deposits upon storage due to the catalyzed degradation of the fuel in the presence of the metal compound. Solutions to this problem other than adding antioxidants to the fuel, which for a variety of reasons is impractical, is to use a combination of metal compounds such as suggested in U.S. Pat. Nos. 2,338,578 and 3,348,932, discussed above. As disclosed patents, however, this approach does not avoid the problem entirely but only gives limited storage stability and represents an expensive alternative.
Another alternative for solving the problem is disclosed in the United Kingdom Patent Application No., 2,098,086A, which discloses a filtering apparatus. It is disclosed that a powdery transition metal compound, (e.g., cuprous chloride) is metered in a specific quantity to the exhaust gas upstream of the filtering apparatus. This solution clearly is not as economical or desirable as admixing an additive to a fuel in a storage container. Other alternatives or solutions to this problem are not found in the art.
Metal complexes of nitrogen compounds for use in lubricant and fuel compositions are known and disclosed in the literature. In U.S. Pat. No. 4,093,614, for example, multiple metal complexes of amine compounds are disclosed. One of the amine complexing agents may be a Mannich base.
U.S. Pat. No. 4,393,179 discloses a synthetic resin containing a metal complex which is derived from a Mannich base and an epoxide resin. These resins find use as a film forming component in various electrocoating lacquers and other coatings. U.S. Pat. No. 4,495,327 also discloses an electrocoating composition wherein the binder is a metal complex resin derived from various vinyl monomers and a complexing ligand such as oximes, dioximes, amines and Mannich bases.
The use of oximes as chelating agents or complexing agents for metal compounds and particularly for use in the extraction or recovery of various metal values from various waste streams has also been well documented. U.S. Pat. Nos. 3,981,966; 3,925,472; 4,020,106; 4,043,882; and 4,142,952 and C & EN, Jan. 14, 1985, pages 58 and 59, all disclose various oximes used to extract metal ions, particularly copper, nickel and zinc from various liquid streams.
None of the above-discussed patents and publications disclose nor even suggest the invention disclosed and claimed herein, i.e., an improved fuel composition comprising a major amount of a fuel and a minor amount of a metal compound and an oxime.